The present invention relates to apparatuses and methods for monitoring the condition of a tire in a vehicle, and, more particularly, to techniques for determining which of several transmitter devices located respectively in the tires has transmitted data.
Conventionally, the condition of each tire is monitored in a passenger compartment of the vehicle using a wireless tire condition monitoring apparatus. More specifically, a transmitter device is attached to each tire. The transmitter device measures, for example, the pressure and temperature in the corresponding tire. The transmitter device wirelessly transmits data that represents the measurements, or the condition of the tire. A receiver is installed in the vehicle""s body frame and receives data from the transmitter devices.
Each transmitter device transmits data that represents the condition of the corresponding tire to the single receiver. When the receiver receives data from one transmitter device, the receiver must determine which tire corresponds to the data. For this purpose, each transmitter device has a specific identification code (ID code). The transmitter device transmits the ID code together with the data that represents the condition of the tire. The receiver thus determines which transmitter device has transmitted the data in accordance with the ID code.
However, in this case, the receiver must pre-store the ID codes of the transmitter devices that are attached to the corresponding tires. Further, when performing an initial entry of the ID codes in the receiver, each ID code must be associated with the position of the tire corresponding to the transmitter device that matches the ID code. Thus, every time a tire is replaced or the position of the tire is changed with respect to the vehicle, the initial entry must be repeated. Since this initial entry is done manually, the operation is complicated and time-consuming.
Accordingly, it is an objective of the present invention to provide an apparatus and a method for monitoring the condition of a tire that automatically determine which transmitter device has transmitted data, thus making it unnecessary to perform an initial entry of transmitter devices"" ID codes.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, the invention provides a tire condition monitoring apparatus for monitoring the condition of a plurality of tires attached to a vehicle. The tires include left and right front tires and left and right rear tires. A transmitter device is attached to each tire. The transmitter device has a condition sensor that detects the condition of the corresponding tire and a signal generator that generates a specific pattern signal when the tire rotates. The pattern signal generated by the signal generator of the transmitter device attached to each left tire is different from the pattern signal generated by the signal generator of the transmitter device attached to each right tire when the vehicle moves in a given direction. Each transmitter device transmits a radio signal that includes data that represents the tire condition and data that represents the pattern signal. A front reception antenna is installed in a body of the vehicle at a position that is relatively near to the left and right front tires. The front reception antenna receives radio signals from the transmitter devices. A rear reception antenna is installed in the vehicle body at a position that is relatively near to the left and right rear tires. The rear reception antenna receives radio signals from the transmitter devices. A receiver receives reception signals from the front and rear reception antennas. The receiver includes a controller. When one of the transmitter devices has transmitted a radio signal, the controller determines which transmitter device has transmitted the radio signal in accordance with the level of reception signals from the reception antennas and the data that represents the pattern signal, which is included in the radio signal transmitted by the transmitter device.
The present invention also provides a tire condition monitoring method for monitoring the condition of a plurality of tires attached to a vehicle. The tires include left and right front tires and left and right rear tires. The method includes detecting the condition of each tire; generating a specific pattern signal for each tire when the tires rotate, wherein the pattern signal generated for each left tire is different from the pattern signal generated for each right tire; transmitting a radio signal from one of the tires, the radio signal including data that represents the tire condition and data that represents the pattern signal; receiving the radio signal at a front location that is relatively near to the front tires; receiving the radio signal at a rear location that is relatively near to the rear tires; and determining which tire has transmitted the radio signal in accordance with the level of signals received at the front and rear locations and the data that represents the pattern signal, which is included in the transmitted radio signal.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.